Safety block



M'arh 9, 1943. 'R w, HEDENBERG 2,313,437

ASAFE'N; BLOCK Filed March, 6 1942 2 Sheets-Sheet 1 March 9., 1943. R. w, HEDENBE'RG y 2,313,437

SAFETY BLOCK Filed March 6. 1942 2 Sheets-Shea?l 2 fraz/enf on; el

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Patented Mar. 9, 1943 UNITED STATES PATENTA OFFICE SAFETY BLOCK Roy Hedenberg, Brooklyn, N. Y.

Application March 6, 1942, Serial No. 433,566

(Gl. 18S-188) 13 Claims.

This invention relates to hoisting gear and more particularly to safety hoisting tackle blocks, though it is noted that in some of the broader claims the invention is not limited to blocks nor to safety hoisting gear.

Objects of the invention are to prevent accidents and possible loss of life when the hoisting rope or cable breaks, and to provide an improved device or apparatus of this kind which will automatically clamp and hold the hoisting rope or cable in the block, should the rope break, thereby to prevent the fall of the scaifold or other structure or object held by the hoisting device.

Other objects of the invention are to provide an improved device of this kind having improved rope clamping means of general application.

Additional objects of the invention are to effect simplicity and eciency in such apparatus and to provide a simple device or apparatus of this kind which is durable, reliable and easy in operation, and economical to manufacture.

Still other objects of the invention will appear as the description proceeds; and while herein details of the invention are described in the specification and some of the claims, the invention as described in the broader claims is not limited to these, and many and various changes may be made without departing from the scope of the invention as claimed in the broader claims.

The inventive features for the accomplishment of these and other objects are shown herein in connection with a safety hoisting block which briefly stated, includes a main frame having side plates having a transverse shaft therein on which the sheave is rotatable in a vertical plane. Each side face ofthe sheave is formed with a hub or boss having peripheral ratchet teeth, a peripheral flange having its inner face formed with cams, and an annular groove between the hub and flange. A chock frame comprises side members pivoted on the shaft on both sides of the sheave, and an upper yoke normally above said shaft and sheave and provided with an upper chock groove in said plane flaring toward its ends. The main frame is provided near said ends with chock blocks, each having on its inner face in said plane a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the chock frame is pivotally moved. Pawls pivoted in said grooves on said side members normally clear the teeth but are thrown by the cams, on excessive speed of the sheave in either direction, as when the'rope breaks, to engage the teeth, thereby to rotate the chock frame and clamp the rope between the chock grooves of the yoke and one of the chock blocks.

Should the hoisting rope break, the block will descend at increased speed, thus speeding up the sheave, causing the pawls to engage the ratchet teeth thus locking the chock frame with the sheave and clamping the rope as explained. While the drawings show the invention as applied to the lower block, the invention may be easily applied to the upper block or to both blocks, or to hoisting gears mounted on fixed foundations.

In the accompanying drawings showing, by way of example, one of many possible embodiments of the invention,

Fig. 1 is a front elevation showing the interior of the block assembly, a side plate being removed; Y

Fig. 2 is a longitudianl vertical sectional View, partly in elevation, showing the assembly in clamped position;

Fig. 3 is a transverse vertical sectional view, partly in elevation, showing the block, the section being taken substantially on the center line of Fig. l, looking toward the right;

Fig. 4 is a transverse horizontal view, showing the block, the section being taken substantially on the line 4 of Fig. 2, looking in the direction of the arrows of said line; I

Fig. 5 is a side elevation showing the sheave and the chock'frame yoke, one of the side members of the chock frame being partly cut away; and

Fig. 6 is a perspective of the chock frame side member. 'Y

The safety hoisting block as herein shown com-v prises a pair of side plates Il! connected by a top wall Il having rope-receiving openings l2,and upper and lower side walls 14, I4 and l5 secured between the margin of the plates to form a frame or housing. A becket strap I6 comprising a bottom hook end |8,has side straps I9 secured against the side plates and having slightly inturned upper ends 2'!) having a bolt 2| passing therethrough to form the becket end. v

A shaft 22 secured in alined openings 24 of the side plates carries a sheave 25 having an oil-less bearing 26 rotatable on said shaft, and having its groove 28 substantially tangential to the axes of the rope openings I2 of the top wall Il whereby the rope 29 may pass through one opening, around the groove and out through the other opening. Each side face of the sheave is provided with a deep wide annular groove coaxial with the sheave forming a central hub or boss 30 and a peripheral flange 3|. Spacer sleeves 32 on the shaft between the sheave and the side plates carry a pivotal chock frame generally denoted by 34 comprising an upper block or yoke 35 disposed in said groove 28 and between the sheave and said top Il, and side members 36 secured to the yoke and engaging between the sheave and side plates I0 and having bearing openings 38 (Fig. 4) received on said sleeves 32'. 'I'he upper face of said yoke is provided with an upper longitudinal rounded chock groove or jaw 36 (Fig. 3), the mid-part 40 (Fig. 2) of which is shallowest and most remote from the sheave, the groove flaring toward its ends 4| and almost merging with the groove of the sheave.

Each upper side wall |4 and I4 of the hoisting block is formed into a chock block 42 proing chock jaw or groove 44 shallowest and nearest the sheave at the lower part and providedwith a bump 41 normally clearing the rope, and positioned to clamp the rope between itself and the upper chock groove when the frame is suiciently pivotally moved on the sleeves 32 and so hold the rope against further passage. The chock frame side members 36 extend beyond said groove at the upper part only; and the inner face .of each side member is formed with a circular thickened portion 43 surrounded by the flange 3|. Each side member is provided on the outer face with an arcuate peripheral groove 45 (Fig. 1) more than 90 degrees in length terminating at the lower part of the side member with a radially disposed shoulder 45, said side members being of identical construction, so that the shoulders on opposite sides of the block are faced in opposite directions.

Fulcrum or pivot posts 48 are mounted across the lower part of the interior of the block between the side plates near the lower side walls, each post having a reduced bearing end in the plane of the adjacent arcuate groove carrying a lever 46Yintermediately fulcrumed on such reduced end and having a long arm 50 engaged with the adjacent shoulder 46. Coiled springs 52 are strained between a retaining post 53 in the lower part of the housing and the mid-part of each long arm 50 to yieldably force the long arms inwardly against said shoulders. Stop posts 54 engaged by short arms 5l respectively of said levers limit the inward Ymovement of said long arms to positions which will hold said frame upright with its upper yoke above the sheave between the rope parts just beneath said openings The peripheral face of the hub at each groove is formed with a set of ratchet teeth 55 (Fig. 5), theY teeth of the respective sets being pointed in opposite directions. The face of each flange is formed therearound adjacent to the groove with an annular series of long cams 56 on the opposite wall of the groove from the ratchet teeth.

The lower half of each of said thickened portions V43 has thereon a pawl retaining frame or cage 58 Within the groove, said cage comprising end lugs 56 integral with ror mounted on said portion and an arcuate connecting piece 66 carried by the lugs and spaced from said portion to form a pawl-receiving space receiving a normally approximately horizontal curved pawl 6| having one end mounted on the side member by means of a pivot 63, theother end having an upturned hook normally clearing the ratchet teeth. The respective pawls are pivoted at opposite ends in order to cooperate with the ratchet teeth. The

intermediate part of each pawl is downwardly curved and normally rests on or between said long cams, said pawls in normal operation being engaged and slightly raised by the moving cams, but not raised high enough to engage the teeth during normal operation. The teeth, the cams and the pawl are so disposed relative to each other that when the downwardly curved part 62 of the pawl is resting in a valley 64 between the cams, the pawl hook will be just under and out of contact with an adjacent ratchet tooth; and when said part is resting on the highest part of the cam, the pawl hook 65 will be in the path of teeth, but about half way between adjacent teeth, and will not engage the teeth. The pawl is adapted, during excessive speed of the sheave 25, to be struck by the cams 56 and thrown into locking engagement with the teeth, whereby the chock frame 34 (Fig. 1) is rotated with the sheave and the rope 29 is clamped between the chock grooves. The holding faces of the teeth and hook 65 are backwardly inclined or undercut, so that when the hook has lockingly vengaged a tooth, the pawl will not leave the tooth so long as holding pressure of the tooth on the pawl is maintained.

The operation will be easily understood from the foregoing. If the rope or cable portion 29 on the left (Fig. 1) should break above the block, the block will begin to descend, increasing the speed of the sheave 25 in a counterclockwise direction on Fig. l, immediately causing the cams 56 to knock the pawl 6| (at the back of the block as in Fig. 2) into engagement with ratchet teeth 55, causing thechock frame 34 to partake of the rotation of the sheave and throw the yoke 35 to the position of Fig. 2, thus clamping the rope between the yoke and block 42 with a wedg-k ing action, thus holding the block and its load against further downward movement. After the load has been otherwise taken care of, the rope may be pulled upon as at the left of Fig. 1, thus unwedging it from the chock block, whereupon one of the springs 52 will restore the chock frame A to normal position, after which a new rope may be supplied to the block rendering the device again ready for use.

In similar manner, if the rope section to the right of Fig. 1 breaks, the pawl 6| (at the front of the block as in Fig. 2) on the other chock frame side member will engage the other set of teeth and the chock frame be rotated in the opposite direction and engage the opposite chock block |4'.

The invention claimed is:

1. A safety hoisting block comprising a main frame; a transverse shaft therein; a rope-receiving sheave rotatable on the shaft in a vertical plane; each side of the sheave having a hub having peripheral ratchet teeth, a peripheral flange having its inner face formed with cams, and an annular groove between the hub and flange; a cho-ck frame comprising side members pivoted on the shaft on both sides of the sheave, and an upper yoke normally held above said shaft and sheave provided with an upper chock groove in said plane flaring toward its ends; the main frame being provided near said ends with chock blocks, each having on its inner face in said plane a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the frame is pivotally moved; and pawls in said grooves pivoted to the side members and thrown by said cams, during excessive speed of the sheave in either direction, into engagement with the teeth, to rotate the chock frame and clamp the rope between the chock grooves of the yoke and one of the chock blocks.

2. A safety hoisting block comprising a main frame; a rope-receiving sheave rotatable therein in a substantially vertical plane; a side of the sheave having a hub having peripheral ratchet teeth, and a peripheral flange having its inner face formed with cams; a chock frame pivoted for movement substantially coaxial with the sheave and provided with an upper yoke provided on its upper face in said plane with an upper chock groove flaring toward its end; the main frame being provided near the smaller end of said groove with a chock block having on its inner face in said plane a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the frame is pivotally moved toward the block; means to yieldably hold said frame with its yoke above the hub; a Pawl pivoted to the chock frame and having an upturned hook; the pawl in normal operation being positioned to rest on the cams out of engagement with the teeth, and positioned and adapted during excessive speed of the sheave to be thrown by the cams into engagement with the teeth, and rotate the chock fraine to the chock block and clamp the rope between the chock grooves of the yoke and block.

3. A hoisting block as in claim 2, said pawl being downwardly curved at its intermediate part; the teeth, the cams and the pawl being so disposed relative to each other that when the downwardly curved part of the pawl is resting in a valley between the cams, the pawl hook will be just under and out of contact with an adjacent ratchet tooth, and when said part is resting on the highest part of the cam, the pawl hook will be about half way between adjacent teeth but will not engage the teeth but will be in the oath of teeth.

4. A hoisting block as in claim 2, the holding faces of the teeth and hook being backwardly inclined or undercut, so that when the hook has lockingly engaged a tooth, the pawl will not leave lthe tooth so long as holding pressure of the tooth on the pawl is maintained.

5. A safety hoisting block comprising a, main frame; a sheave rotatable therein in a substantially vertical plane; a chock'frame pivoted for movement coaxial with the sheave and provided with a, yoke provided in its upper face with an upper chock groove in said plane flaring toward its end; means to yieldably hold said frame with its yoke above the axis of the sheave; the main frame being provided with a chock block having on its inner face in said plane a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the frame is suiiiciently pivotally moved; means set in operation by excessive speed of the sheave to rotate said chock frame to a position to clamp the rope between the chock grooves of the yoke and block.

6. A safety hoisting block comprising side plates and walls secured between the margins of the plates and having upper rope-receiving openings; a shaft secured across the block between the side plates; a sheave rotatable on said shaft, whereby rope may pass through said openings and around the groove; each side face of the sheave being provided with an annular groove forming a peripheral ange and a boss having peripheral ratchet teeth, the teeth of the bosses pointing in opposite directions; the inner face of each ange having long cams; a chock frame comprising an upper yoke between the sheave and wall, and side members pivoted to the shaft;

said yoke having an upper longitudinal chock 5 groove flaring toward both ends, the walls being provided on the inner face with a downwardly tapering chock groove positioned to clamp the rope between its groove and the upper groove when the frame is pivotally moved on the shaft; means to yieldably hold said frame upright; a pawl disposed within the lower part of each gro-ove and having one end pivoted with the side member, the other end having an upturned hook; the pawl in normal operation being not raised high enough by the cams to engage the teeth, but being adapted during excessive speed of the sheave to be thrown by the cams to engagement with the teeth, whereby the frame is rotated and the rope clamped between chock grooves.

7. A safety hoisting block comprising a main frame; a transverse shaft therein; a sheave rotatable on the shaft in a vertical plane; each side of the sheave having a hub and a peripheral flange and an annular groove between the hub and flange; a chock frame comprising side members pivoted on the shaft on both sides of the sheave, and an upper yoke normally above said shaft and sheave provided with an upper chock groove in said plane flaring toward its ends; the main frame being provided near said ends with chock blocks, each having on its inner face in said plane a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the frame is pivotally 35 moved; and means in said groove carried by the set in operation by excessive speed of the sheave in either direction to rotate the chock frame in said direction and clamp the rope between the chock grooves of the yoke and one of the chock blocks.

8. A hoisting block as in claim 7, each chock frame side member having a circular thickened portion surrounded by the flange; each side member being provided on the outer face of said portion with an arcuate peripheral groove more than 90 degrees in length and terminating at the lower part of the side member with a radially disposed shoulder; said side members being of identical construction, so that the shoulders on opposite sides of the block are faced in opposite directions; fulcrum posts mounted across the lower part of the interior of the main frame, each having a reduced bearing end in the plane of the adjacent arcuate groove; a lever intermediately fulcrumed on each of said reduced ends and having a long arm engaged with the adjacent shoulder and a short arm; a retaining post in the lower part of the frame; coiled springs strained between said retaining post and the mid-part of each long arm to yieldably force the long arms inwardly against said shoulders; stop posts engaged by said short arms respectively to limit the inward movement of said long arms to positions which will yieldably hold said frame with the yoke in normal position.

9. A safety hoisting block comprising a main frame; a transverse shaft therein; a sheave rotatable on the shaft in a vertical plane; each side of the sheave having a hub having peripheral ratchet teeth, a peripheral flange having its inner face formed with cams, and an annular groove between the hub and sheave; a chock frame comprising side members pivoted on the shaft on both sides of the sheave, and an upper yoke normally above said shaft and sheave provided with an upper chock groove .in saiol plane aring toward its ends; 'the main vframe being provided near said ends with blocks, each having a chock groove positioned to clamp the rope between itself and the upper groove when the frame is pivotally moved; the inner face of each side member being formed with `a circular thickened portion surrounded by the flange, the lower half of said portion having thereon a pawl retaining cage within the groove comprising end lugs integral with or mounted on said portions and an arcuate connecting piece carried by the lugs `and spaced from said portion to form a pawl-receiving space; 'a curved pawl disposed in said space and having one end pivoted therein,

the other end having an upturned hook normally clearing the ratchet teeth; the intermediate part of the pawl being downwardly curved and normally resting on said cams, said pawls being engaged Vand raised by the moving cams, but not raised high enough to engage the teeth except when the speed of the sheave is excessive.

10. A safety hoisting block comprising a main frame; a sheave rotatable in said frame adapted to receive a rope therearound; a chock .frame pivoted for movement coaxial with the sheave and provided with an upper yoke provided vin its upper face with an upper longitudinal chock groove in the plane of the sheave flaring toward its end; a chock block in the side of the frame near said flaring end provided on the inner face in the plane of the sheave with a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the frame is pivotally moved; means to yieldably hold said frame with its yoke above the sheave; and means to rotate the frame toward block to clamp the rope in the grooves.

11. A block as in claim 10, said last named means comprising means to lock said chock frame to the sheave, whereby the frame is rotated and the rope clamped between the grooves of the yoke and the chock block.

12. A safety hoisting block comprising a frame; a sheave rotatable in said frame adapted to receive a rope therearound; each side of the sheave being provided with a boss and a peripheral flange; the hub having peripheral ratchet teeth, the teeth of the respective bosses being pointed in opposite directions; the inner face of each flange being formed therearound with long cams; a chock frame pivoted for movement coaxial with the sheave and provided with an upper yoke provided with an upper longitudinal chock groove in the plane of the sheave flaring toward its ends; a chock block in each side of the frame provided on the inner face in the plane of the sheave with a downwardly tapering chock groove positioned to clamp the rope between itself and the upper groove when the frame is pivotally moved; means to yieldably hold said frame with its yoke above the sheave; pawls on the chock frame and each having an upturned hook; the pawls normally resting on cams below the sheave out of engagement with the teeth and positioned and adapted during excessive speed of the sheave to be thrown by the cams to engagement with the teeth, whereby the frame is rotated and the rope clamped between the grooves of the yoke and the chock block.

13. A safety hoisting block comprising a main frame; a sheave rotatable therein in a substantially vertical plane; a side of the sheave having a hub having peripheral ratchet teeth, acutely pointed in the normal direction of rotation of the sheave; means coaxial with the sheave for clamping a rope against said frame; a pawl having one end pivoted to said means, the other end being provided with a barb adapted to engage said teeth, and means for causing engagement of said barb and teeth when the sheave attains excessive speed whereby the first mentioned means may be rotated, said teeth being acutely pointed in said direction so that the barb may be deeply engaged therewith until the rotation of the sheave is reversed.

ROY W. HEDENBERG. 

